Substrate processing method and substrate processing apparatus

ABSTRACT

A substrate processing method includes a substrate holding step of holding a substrate in a horizontal attitude, a chemical liquid supply step of supplying a chemical liquid to a main surface of the substrate while rotating the substrate around a vertical rotational axis that passes through a central portion of the substrate, a processing-height maintaining step of maintaining a cylindrical first guard that captures a chemical liquid expelled from the substrate at a processing height position in parallel with the chemical liquid supply step, and a cleaning-height maintaining step of maintaining the first guard at a cleaning height position set below the processing height position in parallel with the chemical liquid supply step after the processing-height maintaining step.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application is a divisional of U.S. patent application Ser.No. 16/361,304, filed on Mar. 22, 2019, which claims the benefit ofpriority to Japanese Patent Application No. 2018-057502, filed on Mar.26, 2018. The entire contents of both of these applications are herebyincorporated herein by reference.

BACKGROUND OF THE INVENTION 1. Field of the Invention

The present invention relates to a substrate processing method and asubstrate processing apparatus. Examples of substrates to be processedinclude semiconductor wafers, substrates for FPDs (flat panel displays)such as liquid crystal displays, etc., plasma displays, or organic EL(electroluminescence) displays, substrates for optical disks, substratesfor magnetic disks, substrates for magneto-optical disks, substrates forphotomasks, ceramic substrates, and substrates for solar cells, etc.

2. Description of Related Art

U.S. Unexamined Patent Application Publication No. 2018/025922 A1discloses a single-substrate processing type apparatus that processessubstrates one by one. A processing unit of the substrate processingapparatus includes a spin chuck that rotates a substrate whilehorizontally holding the substrate, a chemical liquid nozzle that expelsa chemical liquid toward an upper surface of a substrate held by thespin chuck, and a cylindrical processing cup that surrounds the spinchuck. A flow space into which a chemical liquid that has been used forsubstrate processing is guided is defined in the processing cup.

Also, the processing unit of United States Patent ApplicationPublication No. 2018/025922 is configured to collect a chemical liquidthat has been used for substrate processing so that the recoveredchemical liquid can be reused in subsequent steps. Therefore, thesubstrate processing apparatus additionally includes a chemical liquidtank that stores a chemical liquid that is supplied to the chemicalliquid nozzle and a recovery piping that guides a chemical liquid fromthe flow space to the chemical liquid tank. The processing cup includesa guard that has an inner wall serving to capture a processing liquidscattering from around the substrate.

Also, U.S. Unexamined Patent Application Publication No. 2015/090301 A1describes a technique in which the inner wall of the guard is cleanedwith a cleaning liquid, so that extraneous substances adhering to theinner wall are removed. More specifically, U.S. Unexamined PatentApplication Publication No. 2015/090301 A1 discloses that the scatteringdirection of a rinse liquid (a cleaning liquid) scattering from asubstrate in parallel with a rinsing step is changed, and henceextraneous substances are removed from the inner wall of the guard byuse of the rinse liquid.

SUMMARY OF THE INVENTION

Substrate processing performed in the processing unit includes cleaningin which contaminants, such as particles, etc., or to-be-removedsubstances, such as resists, etc., (hereinafter referred to collectivelyas “contaminants”) are removed from a substrate and etching in whichfilms are removed from a substrate. Therefore, there is a fear thatforeign substances, such as these contaminants and films, etc., will beincluded in a chemical liquid expelled from the substrate. The chemicalliquid including such foreign substances is required to be restrained orprevented from being recovered.

Therefore, it is conceivable that a chemical liquid captured by theguard in parallel with a period in which a chemical liquid expelled fromthe substrate includes foreign substances is thrown away whereas achemical liquid captured by the guard in parallel with a period in whicha chemical liquid expelled from the substrate does not include foreignsubstances is recovered.

However, a chemical liquid including foreign substances and a chemicalliquid not including foreign substances are caught by the shared guard,and therefore there is a fear that the foreign substances will betransferred to the chemical liquid not including foreign substancesthrough the inner wall of the guard. As a result, there is a fear thatforeign substances will mix with the chemical liquid that does notoriginally include foreign substances.

Therefore, in the processing cup, the chemical liquid including foreignsubstances is required to be removed from the inner wall of the guard.

Also, the cleaning mentioned in United States Patent ApplicationPublication No. 2015090301 is processing to be executed in rinsing thatis performed after chemical-liquid processing (processing in which achemical liquid is used). Therefore, the cleaning mentioned therein isinapplicable to the present case in which a chemical liquid is removedin parallel with chemical-liquid processing.

That is, in parallel with chemical-liquid processing, it has beendesired to remove remaining foreign substances from the inner wall ofthe guard.

Therefore, an object of the present invention is to provide a substrateprocessing method and a substrate processing apparatus capable ofexcellently removing remaining foreign substances from the inner wall ofthe guard.

The present invention provides a substrate processing method including asubstrate holding step of holding a substrate in a horizontal attitude,a chemical liquid supply step of supplying a chemical liquid to a mainsurface of the substrate while rotating the substrate around a verticalrotational axis that passes through a central portion of the substrate,a processing-height maintaining step of maintaining a cylindrical firstguard that captures a chemical liquid expelled from the substrate at aprocessing height position in parallel with the chemical liquid supplystep, and a cleaning-height maintaining step of maintaining the firstguard at a cleaning height position set below the processing heightposition in parallel with the chemical liquid supply step after theprocessing-height maintaining step.

A large amount of foreign substances are included in a chemical liquidexpelled from the substrate for a time after the chemical liquid supplystep is started. That is, a chemical liquid including foreign substancesis introduced into the processing cup. With the lapse of time after thechemical liquid supply step is started, chemical-liquid processing inthe substrate progresses, and the amount of foreign substances includedin the chemical liquid expelled from the substrate becomes smaller.Thereafter, when a predetermined period of time elapses after thechemical liquid supply step is started, foreign substances come not tobe included in the chemical liquid expelled from the substrate. Theexpression “foreign substances are not included in the chemical liquid”semantically includes a case of “foreign substances are not included inthe chemical liquid at all,” a case of “foreign substances are hardlyincluded in the chemical liquid,” and a case of “only a tiny amount offoreign substances are included in the chemical liquid.”

With this method, in the chemical liquid supply step, the first guard ispositionally changed to the cleaning height position set below theprocessing height position from the processing height position at whichthe first guard has been so far arranged, and then the first guard ismaintained at the cleaning height position for a predetermined period oftime.

Both in a state in which the first guard is arranged at the processingheight position and in a state in which the first guard is arranged atthe cleaning height position, a chemical liquid expelled from thesubstrate is captured by the inner wall of the first guard. The chemicalliquid captured by the inner wall of the first guard flows downwardlybecause of its own weight.

From a viewpoint based on the inner wall of the first guard, a region inthe inner wall to capture a chemical liquid is positionally higher in astate in which the first guard is arranged at the cleaning heightposition than in a state in which the first guard is arranged at theprocessing height position. Therefore, it is possible to excellentlywash away a chemical liquid captured by the first guard arranged at theprocessing height position (i.e., excellently wash away a chemicalliquid including foreign substances) by means of a chemical liquidcaptured by the first guard arranged at the cleaning height position.This makes it possible to excellently remove remaining foreignsubstances from the inner wall of the first guard.

In one preferred embodiment of the present invention, the processingheight position is a height position that enables capturing a chemicalliquid expelled from the substrate in a first region. The cleaningheight position is a height position that enables capturing a chemicalliquid expelled from the substrate in a second region that is set abovean upper end of an arrival region to which the chemical liquid capturedin the first region is reachable.

With this method, the second region is set above the upper end of thearrival region to which the chemical liquid captured in the firstregion, which the inner wall of the first guard arranged at theprocessing height position captures, is reachable. Therefore, it ispossible to excellently wash away substantially all of the chemicalliquid including foreign substances, which adhere to the inner wall ofthe first guard, by means of the chemical liquid captured by the firstguard arranged at the cleaning height position.

In one preferred embodiment of the present invention, the substrateprocessing method further includes a guard switching step of, after thecleaning-height maintaining step, switching a guard arranged at aposition that enables capturing a chemical liquid expelled from thesubstrate from the first guard to a cylindrical second guard providedseparately from the first guard.

With this method, prior to the switching of the guard arranged at aposition that enables capturing a chemical liquid from the first guardto the second guard, the first guard is positionally changed to thecleaning height position from the processing height position at whichthe first guard has been so far arranged. Thereafter, the first guard ismaintained at the cleaning height position for a predetermined period oftime. Prior to guard switching, the first guard is arranged at thecleaning height position so as to clean the inner wall of the firstguard, and therefore it is possible to remove a resist from the innerwall of the first guard before finishing the use of the first guard.

In one preferred embodiment of the present invention, the guardswitching step includes a step of, after the cleaning-height maintainingstep, switching a guard arranged at a position that enables capturing achemical liquid expelled from the substrate from the first guard to thesecond guard without again executing the processing-height maintainingstep.

With this method, it is possible to perform guard switching immediatelyafter the first guard is cleaned. Hence, it is possible to shorten theprocessing time.

As in one preferred embodiment of the present invention, the substrateprocessing method may further include a different-liquid supply step ofsupplying the substrate with another processing liquid differing in kindfrom a chemical liquid supplied to the substrate while rotating thesubstrate around the rotational axis and a step of placing the firstguard at a position that enables capturing another processing liquidexpelled from the substrate in parallel with the different-liquid supplystep.

A resist may be formed on the main surface of the substrate. Also, achemical liquid supplied to the main surface of the substrate in thechemical liquid supply step may include an SPM.

In the chemical liquid supply step, a resist formed on the substrate isremoved by an SPM. A large amount of resist residues are included in theSPM expelled from the substrate after the chemical liquid supply step isstarted. Therefore, there is a fear that resist residues will remain inthe inner wall of the first guard by allowing the inner wall of thefirst guard to capture an SPM that includes a large amount of resistresidues.

With this method, it is possible to excellently remove remaining resistresidues from the inner wall of the first guard.

The present invention provides a substrate processing apparatusincluding a substrate holding unit that holds a substrate, a rotationunit that rotates a substrate held by the substrate holding unit arounda rotational axis passing through a central portion of the substrate, achemical liquid supply unit that supplies a chemical liquid to asubstrate held by the substrate holding unit, a first guard thatsurrounds a periphery of the substrate holding unit and that captures aliquid expelled from a substrate held by the substrate holding unit, aguard elevating/lowering unit that raises and lowers the first guard,and a controller that controls the rotation unit, the chemical liquidsupply unit, and the guard elevating/lowering unit, and the controllerexecutes a chemical liquid supply step of supplying a chemical liquid tothe substrate while rotating the substrate around the rotational axis, aprocessing-height maintaining step of maintaining a cylindrical firstguard at a processing height position in parallel with the chemicalliquid supply step, and a cleaning-height maintaining step ofmaintaining the first guard at a cleaning height position lower than theprocessing height position in parallel with the chemical liquid supplystep after the processing-height maintaining step.

With this arrangement, in the chemical liquid supply step, the firstguard is positionally changed to the cleaning height position set belowthe processing height position from the processing height position atwhich the first guard has been so far arranged, and then the first guardis maintained at the cleaning height position for a predetermined periodof time.

A large amount of foreign substances are included in the chemical liquidexpelled from the substrate after the chemical liquid supply step isstarted. With the lapse of time after the chemical liquid supply step isstarted, chemical-liquid processing in the substrate progresses, and theamount of foreign substances included in the chemical liquid expelledfrom the substrate becomes smaller. Thereafter, when a predeterminedperiod of time elapses after the chemical liquid supply step is started,foreign substances come not to be included in the chemical liquidexpelled from the substrate.

A chemical liquid including foreign substances is captured by the firstguard after the chemical liquid supply step is started. Also, after apredetermined period of time elapses, the first guard is positionallychanged to the cleaning height position lower than the processing heightposition.

Likewise, in a state in which the first guard is arranged at thecleaning height position, a chemical liquid expelled from the substrateis captured by the inner wall of the first guard. From a viewpoint basedon the inner wall of the first guard, a region in the inner wall of thefirst guard in which a chemical liquid is captured is arranged at ahigher position in a case in which the first guard is arranged at theprocessing height position than in a case in which the first guard isarranged at the cleaning height position. Therefore, in a state in whichthe first guard is arranged at the cleaning height position, thechemical liquid captured by the inner wall of the first guard flowsdownwardly. Thereafter, this chemical liquid enables cleaning away thechemical liquid including foreign substances captured by the inner wallof the first guard arranged at the processing height position. Hence, itis possible to excellently remove remaining foreign substances from theinner wall of the first guard.

In one preferred embodiment of the present invention, the processingheight position is a height position that enables capturing a chemicalliquid expelled from the substrate in a first region, and the cleaningheight position is a height position that enables capturing a chemicalliquid expelled from the substrate in a second region that is set abovean upper end of an arrival region to which the chemical liquid capturedin the first region is reachable.

With this arrangement, the second region is set above the upper end ofthe arrival region to which the chemical liquid captured in the firstregion, which is captured by the inner wall of the first guard arrangedat the processing height position, is reachable. Therefore, it ispossible to excellently wash away substantially all of the chemicalliquid including foreign substances, which adhere to the inner wall ofthe first guard, by means of the chemical liquid captured by the firstguard arranged at the cleaning height position.

In one preferred embodiment of the present invention, the substrateprocessing apparatus further includes a second guard that is providedseparately from the first guard and that surrounds a periphery of thesubstrate holding unit and that captures a liquid expelled from asubstrate held by the substrate holding unit. The controller furtherexecutes a guard switching step of, after the cleaning-heightmaintaining step, switching a guard arranged at a position that enablescapturing a chemical liquid expelled from the substrate from the firstguard to the second guard.

With this arrangement, prior to the switching of a guard arranged at aposition enabling the capture of a chemical liquid from the first guardto the second guard, the first guard is positionally changed to thecleaning height position from the processing height position at whichthe first guard has been so far arranged. Thereafter, the first guard ismaintained at the cleaning height position for a predetermined period oftime. Prior to guard switching, the first guard is arranged at thecleaning height position, and the inner wall of the first guard iscleaned, and therefore the first guard has already been cleaned when theguard is switched, and a chemical liquid including foreign substancesdoes not adhere to the inner wall of the first guard.

In one preferred embodiment of the present invention, the controllerexecutes a step of, after the cleaning-height maintaining step,switching a guard arranged at a position that enables capturing achemical liquid expelled from the substrate from the first guard to thesecond guard without again executing the processing-height maintainingstep in the guard switching step.

With this arrangement, it is possible to perform guard switchingimmediately after the first guard is cleaned. Hence, it is possible toshorten the processing time.

The substrate processing apparatus may further include adifferent-liquid supply unit that supplies a substrate held by thesubstrate holding unit with one other processing liquid differing inkind from a chemical liquid supplied to the substrate. In this case, thecontroller may further execute a different-liquid supply step ofsupplying the substrate with the one other processing liquid whilerotating the substrate around the rotational axis and a step of placingthe first guard at a position that enables capturing another processingliquid expelled from the substrate in parallel with the different-liquidsupply step.

A resist may be formed on the main surface of the substrate. Also, achemical liquid supplied to the main surface of the substrate in thechemical liquid supply step may include an SPM.

In the chemical liquid supply step, the resist formed on the substrateis removed by the SPM. After the chemical liquid supply step is started,a large amount of resist residues are included in the SPM expelled fromthe substrate. Therefore, there is a fear that resist residues willremain in the inner wall of the first guard by allowing the inner wallof the first guard to capture an SPM that includes a large amount ofresist residues.

With this arrangement, it is possible to excellently remove remainingresist residues from the inner wall of the first guard.

The aforementioned or other objects, features, and effects of thepresent invention will be clarified by the following description ofpreferred embodiments given below with reference to the accompanyingdrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an illustrative plan view to describe a layout of the insideof a substrate processing apparatus according to a preferred embodimentof the present invention.

FIG. 2 is an illustrative sectional view to describe a configurationexample of a processing unit included in the substrate processingapparatus.

FIG. 3 is a block diagram for describing an electrical configuration ofa main part of the substrate processing apparatus.

FIG. 4 is a flowchart for describing a substrate processing exampleperformed by the processing unit.

FIG. 5 is a timing chart for describing an up-and-down timing of a guardin an SPM step.

FIGS. 6A to 6C are illustrative views to describe the SPM step.

FIG. 6D is an illustrative view to describe a drying step.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

FIG. 1 is an illustrative plan view to describe a layout of the insideof a substrate processing apparatus 1 according to a preferredembodiment of the present invention. The substrate processing apparatus1 is a single-substrate processing type apparatus that processesdisk-shaped substrates W, such as semiconductor wafers, etc., one byone.

The substrate processing apparatus 1 includes a plurality of load portsLP each of which holds a substrate container C that contains a substrateW, a plurality of (for example, twelve) processing units 2 each of whichprocesses a substrate W transferred from each of the load ports LP byuse of a processing liquid, such as a chemical liquid, etc., a transferrobot that transfers a substrate W from each of the load ports LP toeach of the processing units 2, and a controller 3 that controls thesubstrate processing apparatus 1. The transfer robot includes an indexerrobot IR that transfers a substrate Won a path between the load port LPand the processing unit 2 and a substrate transfer robot CR thattransfers a substrate W on a path between the indexer robot IR and theprocessing unit 2.

The substrate processing apparatus 1 includes a plurality of fluid boxes4 each of which houses, for example, a valve and a storage box 6 thathouses, for example, a sulfuric-acid tank 27 (see FIG. 2) that storessulfuric acid. The processing unit 2 and the fluid box 4 are disposedinside a frame 5 of the substrate processing apparatus 1, and arecovered with the frame 5 of the substrate processing apparatus 1. Thestorage box 6 may be housed in the frame 5 although the storage box 6 isdisposed outside the frame 5 of the substrate processing apparatus 1 inan example of FIG. 1. The storage box 6 may be a single boxcorresponding to the plurality of fluid boxes 4, or may be provided inthe form of a plurality of boxes corresponding to the plurality of fluidboxes 4 in a one-on-one relationship.

The twelve processing units 2 form four towers disposed so as tosurround the substrate transfer robot CR in a plan view. Each towerincludes three processing units 2 stacked up and down. The four storageboxes 6 correspond to the four towers, respectively. Likewise, the fourfluid boxes 4 correspond to the four towers, respectively. Sulfuric acidstored in the sulfuric-acid tank 27 in each storage box 6 is supplied tothe three processing units 2 corresponding to the storage box 6 throughthe fluid box 4 corresponding to the storage box 6.

FIG. 2 is an illustrative sectional view to describe a configurationexample of the processing unit 2. The processing unit 2 includes abox-shaped chamber 7 that has an internal space, a spin chuck (substrateholding unit) 8 that rotates a substrate W around a vertical rotationalaxis A1 passing through the center of the substrate W while holding thesingle substrate W in a horizontal attitude in the chamber 7, an SPMsupply unit (chemical liquid supply unit) 9 that supplies an SPM(sulfuric acid/hydrogen peroxide mixture, i.e., a mixed liquid includingH₂SO₄ (sulfuric acid) and H₁O₂ (hydrogen peroxide water)), which is anexample of the chemical liquid, to an upper surface of the substrate Wheld by the spin chuck 8, a rinse liquid supply unit (different-liquidsupply unit) 10 that supplies a rinse liquid to the upper surface of thesubstrate W held by the spin chuck 8, and a cylindrical processing cup11 that surrounds the spin chuck 8.

The chamber 7 includes a box-shaped partition wall 12, an FFU (fanfilter unit) 14 serving as a as the blower unit that sends clean airfrom an upper portion of the partition wall 12 to the inside of thepartition wall 12 (which is equivalent to the inside of the chamber 7),and an exhaust device (not shown) that discharges a gas present in thechamber 7 from a lower portion of the partition wall 12.

The FFU 14 is disposed on the partition wall 12, and is attached to aceiling of the partition wall 12 as shown in FIG. 2. The FFU 14 sendsclean air from the ceiling of the partition wall 12 to the inside of thechamber 7. The exhaust device (not shown) is connected to a bottomportion of the processing cup 11 through an exhaust duct 13 connected tothe inside of the processing cup 11, and suctions the inside of theprocessing cup 11 from the bottom portion of the processing cup 11. Adownflow (downward flow) is formed by both the FFU 14 and the exhaustdevice (not shown) in the chamber 7.

A gripping-type chuck that horizontally holds a substrate W whilesqueezing the substrate W in a horizontal direction is employed as thespin chuck 8. Specifically, the spin chuck 8 includes a spin motor(rotation unit) M, a spin shaft 15 formed integrally with a drivingshaft of the spin motor M, and a disk-shaped spin base 16 that issubstantially horizontally attached to an upper end of the spin shaft15.

The spin base 16 includes a horizontal circular upper surface 16a thathas an outer diameter greater than an outer diameter of the substrate W.A plurality of (three or more, e.g., six) gripping members 17 aredisposed on the upper surface 16a at a peripheral edge portion of theupper surface 16a. The gripping members 17 are disposed with suitableintervals therebetween, e.g., with equal intervals therebetween, on acircumference corresponding to an outer peripheral shape of thesubstrate W in the peripheral edge portion of the upper surface of thespin base 16.

The SPM supply unit 9 includes an SPM nozzle 18, a nozzle arm 19 thathas a forward end portion to which the SPM nozzle 18 is attached, and anozzle moving unit 20 that moves the SPM nozzle 18 by moving the nozzlearm 19.

The SPM nozzle 18 is, for example, a straight nozzle that expels an SPMin a continuous flow state. The SPM nozzle 18 is attached to the nozzlearm 19 in, for example, a perpendicular attitude in which a processingliquid is expelled in a direction perpendicular to the upper surface ofthe substrate W. The nozzle arm 19 extends in the horizontal direction.

The nozzle moving unit 20 horizontally moves the SPM nozzle 18 byhorizontally moving the nozzle arm 19 around a swing axis. The nozzlemoving unit 20 horizontally moves the SPM nozzle 18 between a processingposition at which an SPM expelled from the SPM nozzle 18 lands on theupper surface of the substrate Wand a retreat position at which the SPMnozzle 18 is set around the spin chuck 8 in a plan view. In the presentpreferred embodiment, the processing position is, for example, a centralposition at which an SPM expelled from the SPM nozzle 18 lands on acentral portion of the upper surface of the substrate W.

The SPM supply unit 9 additionally includes a sulfuric acid supply unit21 that supplies H₂SO₄ to the SPM nozzle 18 and ahydrogen-peroxide-water supply unit 22 that supplies H₂O₂ to the SPMnozzle 18.

The sulfuric acid supply unit 21 includes a sulfuric acid piping 23 thathas its end connected to the SPM nozzle 18, a sulfuric acid valve 24that opens and closes the sulfuric acid piping 23, asulfuric-acid-flow-rate regulating valve 25 that regulates the flow rateof H₂SO₄ flowing through the sulfuric acid piping 23 while regulatingthe opening degree of the sulfuric acid piping 23, and a sulfuric acidsupply portion 26 to which the other end of the sulfuric acid piping 23is connected. The sulfuric acid valve 24 and the sulfuric-acid-flow-rateregulating valve 25 are housed in the fluid box 4. The sulfuric acidsupply portion 26 is housed in the storage box 6.

The sulfuric-acid-flow-rate regulating valve 25 includes a valve bodyinside which a valve seat is disposed, a valving element that opens andcloses the valve seat, and an actuator that moves the valving elementbetween an opening position and a closing position. The same applies tothe other flow-rate regulating valves.

The sulfuric acid supply portion 26 includes the sulfuric-acid tank 27that stores H₂SO₄ that is to be supplied to the sulfuric acid piping 23,a sulfuric-acid replenishing piping 28 that replenishes sulfuric-acidtank 27 with a new liquid of H₂SO₄, a recovery tank 29, a liquid-feedingpiping 30 that sends H₂SO₄ stored in the recovery tank 29 to thesulfuric-acid tank 27, a first liquid-feeding device 31 that moves H₂SO₄contained in the recovery tank 29 to the liquid-feeding piping 30, asulfuric acid supply piping 32 by which the sulfuric-acid tank 27 andthe sulfuric acid piping 23 are connected together, a temperatureregulator 33 that performs the regulation of temperature while heatingsulfuric acid flowing through the sulfuric acid supply piping 32, and asecond liquid-feeding device 34 that moves H₂SO₄ contained in thesulfuric-acid tank 27 to the sulfuric acid supply piping 32. Thetemperature regulator 33 may be immersed in H₂SO₄ of the sulfuric-acidtank 27, and may be interposed in a halfway portion of the sulfuric acidsupply piping 32 as shown in FIG. 2. The sulfuric acid supply portion 26may additionally include a filter that filters sulfuric acid flowingthrough the sulfuric acid supply piping 32 and/or a thermometer thatmeasures the temperature of sulfuric acid flowing through the sulfuricacid supply piping 32. Although the sulfuric acid supply portion 26 hasthe two tanks in the present preferred embodiment, the configuration ofthe recovery tank 29 may be eliminated, and a configuration in whichsulfuric acid recovered from the processing cup 11 is supplied directlyto the sulfuric-acid tank 27 may be employed. The first and secondliquid-feeding devices 31 and 34 are, for example, pumps, respectively.The pump sucks H₂SO₄ contained in the sulfuric-acid tank 27, and expelsH₂SO₄ sucked thereinto.

The hydrogen-peroxide-water supply unit 22 includes ahydrogen-peroxide-water piping 35 connected to the SPM nozzle 18, ahydrogen-peroxide-water valve 36 that opens and closes thehydrogen-peroxide-water piping 35, and ahydrogen-peroxide-water-flow-rate regulating valve 37 that regulates theflow rate of H₂O₂ flowing through the hydrogen-peroxide-water valve 36while regulating the opening degree of the hydrogen-peroxide-water valve36. The hydrogen-peroxide-water valve 36 and thehydrogen-peroxide-water-flow-rate regulating valve 37 are housed in thefluid box 4. H₂O₂ that has not undergone temperature regulation and thathas normal temperatures (about 23° C.) is supplied from ahydrogen-peroxide-water supply source housed in the storage box 6 to thehydrogen-peroxide-water piping 35.

When the sulfuric acid valve 24 and the hydrogen-peroxide-water valve 36are opened, H₂SO₄ from the sulfuric acid piping 23 and H₂O₂ from thehydrogen-peroxide-water piping 35 are supplied to the inside of a casing(not shown) of the SPM nozzle 18, and are sufficiently mixed (stirred)in the casing. As a result of this mixture, H₂SO₄ and H₂O₂ are evenlymixed together. A mixed liquid (SPM) of H₂SO₄ and H₂O₂ is generated by areaction between H₂SO₄ and H₂O₂. The SPM includes peroxomonosulfuricacid (H₂SO₅) having strong oxidative power, and is heated to atemperature (not less than 100° C.; for example, 160° C. to 220° C.)higher than temperatures of H₂SO₄ and H₂O₂ that have not yet mixedtogether. The SPM generated in this way and having a high temperature isexpelled from an expelling port formed in a front end (for example,lower end) of the casing of the SPM nozzle 18.

It is possible to regulate the concentration of H₂SO₄ of an SPM that isexpelled from the SPM nozzle 18 within a predetermined range byregulating the opening degree of the sulfuric acid piping 23 and that ofthe hydrogen-peroxide-water piping 35 by means of thesulfuric-acid-flow-rate regulating valve 25 and thehydrogen-peroxide-water-flow-rate regulating valve 37. The concentration(mixture ratio) of H₂SO₄ of an SPM that is expelled from the SPM nozzle18 is regulated within the range of H₂SO₄:H₂O₂=20:1 (highly-concentratedstate in which sulfuric acid is rich) to 2:1 (low-concentrated state inwhich hydrogen peroxide water is rich) in the flow ratio, morepreferably, within the range of H₂SO₄:H₂O₂=10:1 to 5:1 in the flowratio.

The sulfuric acid supply portion 26 reuses an SPM recovered from theprocessing cup 11 as H₂SO₄. The SPM recovered from the processing cup 11is supplied to the recovery tank 29, and is stored in the recovery tank29. With the lapse of time, H₂O₂ included in the SPM is decomposed, andthe SPM stored in the recovery tank 29 is changed into sulfuric acid.However, sulfuric acid into which the SPM has been changed includes alarge quantity of water, and therefore there is a need to regulate itsconcentration. In the sulfuric acid supply portion 26, H₂SO₄ containedin the recovery tank 29 is sent to the sulfuric-acid tank 27, andundergoes concentration regulation in the sulfuric-acid tank 27. Hence,the SPM is reused as H₂SO₄.

The rinse liquid supply unit 10 includes a rinse liquid nozzle 47. Therinse liquid nozzle 47 is, for example, a straight nozzle that expels aliquid in a continuous flow state, and is fixedly disposed above thespin chuck 8 such that its expelling port faces the central portion ofthe upper surface of the substrate W. A rinse liquid piping 48 to whicha rinse liquid from a rinse liquid supply source is supplied isconnected to the rinse liquid nozzle 47. A rinse liquid valve 49 thatperforms switching between the supply and the supply stop of a rinseliquid from the rinse liquid nozzle 47 is interposed in a halfwayportion of the rinse liquid piping 48. When the rinse liquid valve 49 isopened, a rinse liquid supplied from the rinse liquid piping 48 to therinse liquid nozzle 47 is expelled from the expelling port formed at alower end of the rinse liquid nozzle 47. When the rinse liquid valve 49is closed, the supply of the rinse liquid from the rinse liquid piping48 to the rinse liquid nozzle 47 is stopped. The rinse liquid is, forexample, deionized water (DIW), and yet, without being limited to DIW,the rinse liquid may be any one of carbonated water, electrolyzed ionwater, hydrogen water, ozone water, ammonia water, and aqueoushydrochloric acid solution having a diluted concentration (e.g., about10 ppm to 100 ppm). Also, the rinse liquid may be used at a normaltemperature, or may be used as warm water by being heated.

Also, the rinse liquid supply unit 10 may include a rinse-liquid-nozzlemoving device that scans the landing position of a rinse liquid withrespect to the upper surface of the substrate W within the plane of thesubstrate W by moving the rinse liquid nozzle 47.

The processing cup 11 is disposed outwardly (in a direction away fromthe rotational axis A1) from the substrate W held by the spin chuck 8.The processing cup 11 is made of, for example, an insulating material.The processing cup 11 surrounds the lateral side of the spin base 16.When a processing liquid is supplied to the substrate W in a state inwhich the spin chuck 8 rotates the substrate W, the processing liquidsupplied to the substrate W is shaken off around the substrate W. Whenthe processing liquid is supplied to the substrate W, an upper endportion 11a of the processing cup 11 that is upwardly open is arrangedabove the spin base 16. Therefore, the processing liquid, such as achemical liquid or water, etc., that has been drained around thesubstrate W is caught by the processing cup 11. Thereafter, theprocessing liquid caught by the processing cup 11 is sent to therecovery tank 29 or to a waste liquid device (not shown).

The processing cup 11 includes a circular cylindrical member 40, aplurality of cups (first and second cups 41 and 42) fixedly disposed soas to doubly surround the spin chuck 8 inside the circular cylindricalmember 40, a plurality of guards (first, second, and third guards 43,44, and 45) each of which catches a processing liquid (chemical liquidor rinse liquid) that has scattered from the periphery of the substrateW, and a guard elevating/lowering unit 46 that independently raises andlowers the respective guards. The guard elevating/lowering unit 46 isconfigured to include, for example, a ball screw mechanism.

The processing cup 11 is collapsible, and is unfolded and folded byallowing the guard elevating/lowering unit 46 to raise and lower atleast one of the three guards.

The first cup 41 has an annular shape, and surrounds the periphery ofthe spin chuck 8 between the spin chuck 8 and the circular cylindricalmember 40. The first cup 41 has a substantially rotationally symmetricalshape with respect to the rotational axis A1 of the substrate W. Thefirst cup 41 cross-sectionally has the shape of the capital letter U,and defines a first groove 50 that is used to collect and drain aprocessing liquid that has been used to process the substrate W. A drainport 51 is bored in a lowest place of a bottom portion of the firstgroove 50, and a first drain piping 52 is connected to the drain port51. A processing liquid introduced into the first drain piping 52 issent to a drain device (not shown; maybe a waste liquid device), and isprocessed by this device.

The second cup 42 has an annular shape, and surrounds the periphery ofthe first cup 41. The second cup 42 has a substantially rotationallysymmetrical shape with respect to the rotational axis A1 of thesubstrate W. The second cup 42 sectionally has the shape of the capitalletter U, and defines a second groove 53 that is used to gather andcollect a processing liquid that has been used to process the substrateW. A drain/recovery port 54 is bored in a lowest position of a bottomportion of the second groove 53, and a common piping 55 is connected tothe drain/recovery port 54. A recovery piping 56 and a second drainpiping 57 are connected in a branching manner to the common piping 55.The other end of the recovery piping 56 is connected to the recoverytank 29 of the sulfuric acid supply portion 26. A recovery valve 58 isinterposed in the recovery piping 56, and a drain valve 59 is interposedin the second drain piping 57. A liquid flowing through the commonpiping 55 is guided to the recovery piping 56 by opening the recoveryvalve 58 while closing the drain valve 59. Likewise, a liquid flowingthrough the common piping 55 is guided to the second drain piping 57 byopening the drain valve 59 while closing the recovery valve 58. That is,the recovery valve 58 and the drain valve 59 function as a switchingunit that performs switching to change the flow destination of a liquidflowing through the common piping 55 between the recovery piping 56 andthe second drain piping 57. When an inner wall 44a of the second guard44, the second cup 42, and the common piping 55 are cleaned, the seconddrain piping 57 is solely used to throw away a cleaning liquid used toclean these components.

The innermost first guard 43 surrounds the periphery of the spin chuck8, and has a substantially rotationally symmetrical shape with respectto the rotational axis A1 of the substrate W by means of the spin chuck8. The first guard 43 includes a circular cylindrical lower end portion63 that surrounds the periphery of the spin chuck 8, a cylindricalportion 64 that extends outwardly (i.e., in a direction receding fromthe rotational axis A1 of the substrate W) from an upper end of thelower end portion 63, a circular cylindrical middle portion 65 thatextends vertically upwardly from an outer peripheral portion of an uppersurface of the cylindrical portion 64, and an annular upper end portion66 that extends obliquely upwardly from an upper end of the middleportion 65 toward the inner side (i.e., in a direction approaching therotational axis A1 of the substrate W). The lower end portion 63 ispositioned on the first groove 50, and is housed within the first groove50 in a state in which the first guard 43 and the first cup 41 areclosest to each other. An inner peripheral edge of the upper end portion66 has a circular shape larger in diameter than the substrate W held bythe spin chuck 8 in a plan view. The upper end portion 66 may besectionally linear as shown in FIG. 2, or may extend, for example, whiledrawing a smooth circular arc.

The second guard 44 that is a second one from the inside surrounds theperiphery of the spin chuck 8 at an outer side of the first guard 43,and has a substantially rotationally symmetrical shape with respect tothe rotational axis A1 of the substrate W by means of the spin chuck 8.The second guard 44 has a circular cylindrical portion 67 coaxial withthe first guard 43 and an upper end portion 68 that extends obliquelyupwardly on the center side (i.e., in a direction approaching therotational axis A1 of the substrate W) from an upper end of the circularcylindrical portion 67. An inner peripheral edge of the upper endportion 68 has a circular shape larger in diameter than the substrate Wheld by the spin chuck 8 in a plan view. The upper end portion 68 maybesectionally linear as shown in FIG. 2, or may extend, for example, whiledrawing a smooth circular arc. A front end of the upper end portion 68defines an opening of the upper end portion 11 a of the processing cup11.

The circular cylindrical portion 67 is positioned on the second groove53. The upper end portion 68 is disposed so as to lie on the upper endportion 66 of the first guard 43 in an up-down direction, and is formedso as to approach the upper end portion 66 with a slight gaptherebetween in a state in which the first guard 43 and the second guard44 are closest to each other.

The outermost third guard 45 surrounds the periphery of the spin chuck 8at an outer side of the second guard 44, and has a substantiallyrotationally symmetrical shape with respect to the rotational axis A1 ofthe substrate W by means of the spin chuck 8. The third guard 45 has acircular cylindrical portion 70 coaxial with the second guard 44 and anupper end portion 71 that extends obliquely upwardly on the center side(i.e., in a direction approaching the rotational axis A1 of thesubstrate W) from an upper end of the circular cylindrical portion 70.An inner peripheral edge of the upper end portion 71 has a circularshape larger in diameter than the substrate W held by the spin chuck 8in a plan view. The upper end portion 71 maybe sectionally linear asshown in FIG. 2, or may extend, for example, while drawing a smoothcircular arc.

In the present preferred embodiment, a first flow space (that is, adrain space) 101 to which a chemical liquid that has been used toprocess the substrate W is guided is defined by the first groove 50 ofthe first cup 41, an inner wall 43 a of the first guard 43, and an outerperiphery of a casing of the spin chuck 8.

A second flow space (that is, a recovery space) 102 to which a chemicalliquid that has been used to process the substrate W is guided isdefined by the second groove 53 of the second cup 42, an outer wall 43 bof the first guard 43, and the inner wall 44a of the second guard 44.The first flow space 101 and the second flow space 102 are isolated fromeach other.

The guard elevating/lowering unit 46 raises and lowers the first tothird guards 43 to 45 between an upper position in which the upper endportion of the guard is arranged above the substrate W and a lowerposition in which the upper end portion of the guard is arranged belowthe substrate W, respectively. The guard elevating/lowering unit 46 canhold each guard at an arbitrary position between the upper position andthe lower position. The substrate W is supplied with a processing liquidor is dried in a state in which any one of the guards (the first,second, or third guard 43, 44, or 45) faces a peripheral end surface ofthe substrate W.

All of the first to third guards 43 to 45 are arranged at the upperposition (processing height position) in a first guard facing state ofthe processing cup 11 (see FIG. 6A) in which the innermost first guard43 is allowed to face the peripheral end surface of the substrate W. Thesecond and third guards 44 and 45 are arranged at the upper position,and, simultaneously, the first guard 43 is arranged at the lowerposition in a second guard facing state of the processing cup 11 (seeFIG. 6C) in which the second guard 44 that is a second one from theinside is allowed to face the peripheral end surface of the substrate W.The third guard 45 is arranged at the upper position, and,simultaneously, the first and second guards 43 and 44 are arranged atthe lower position in a third guard facing state of the processing cup11 (see FIG. 6D) in which the outermost third guard 45 is allowed toface the peripheral end surface of the substrate W. All of the first tothird guards 43 to 45 are arranged at the lower position in a retreatedstate (see FIG. 2) in which all guards are allowed to retreat from theperipheral end surface of the substrate W.

As described later, a first guard cleaning state in which the firstguard 43 is arranged at a cleaning height position WP (see FIG. 6B) setbelow the upper position (processing height position) PP (see FIG. 6A)while placing both the second and third guards 44 and 45 at the upperposition is prepared in addition to the first guard facing state that isa state in which the first guard 43 faces the peripheral end surface ofthe substrate W in the present preferred embodiment.

FIG. 3 is a block diagram for describing an electrical configuration ofa main part of the substrate processing apparatus 1.

The controller 3 is configured by use of, for example, a microcomputer.The controller 3 has an arithmetic unit such as a CPU, etc., a storageunit such as a read-only memory device or a hard disk drive, etc., andan input-output unit. The storage unit includes a computer-readablerecording medium that records a program that is executed by thearithmetic unit. A step group is incorporated in the recording medium soas to allow the controller 3 to perform resist removal processingdescribed later.

The controller 3 controls operations of the spin motor M, the nozzlemoving unit 20, the guard elevating/lowering unit 46, the first andsecond liquid-feeding devices 31 and 34, the temperature regulator 33,etc., in accordance with a predetermined program. Also, the controller 3controls open-close operations of the sulfuric acid valve 24, thehydrogen-peroxide-water valve 36, the rinse liquid valve 49, etc., inaccordance with a predetermined program. Also, the controller 3regulates opening degrees of both the sulfuric-acid-flow-rate regulatingvalve 25 and the hydrogen-peroxide-water-flow-rate regulating valve 37in accordance with a predetermined program.

FIG. 4 is a flowchart for describing a substrate processing exampleperformed by the processing unit 2. The substrate processing examplewill be described with reference to FIG. 1 to FIG. 4.

This substrate processing example is resist-removing processing thatremoves a resist from the upper surface (main surface) of the substrateW. The resist uses an organic substance such as a resin (polymer), etc.,a photosensitizer, an additive, and a solvent as chief constituents.When the substrate processing example is applied to the substrate W bymeans of the processing unit 2, the substrate W that has undergone ionimplantation processing with a high dose is carried into the chamber 7(S1 of FIG. 4). Let it be supposed that the substrate W has notundergone processing for the ashing of the resist.

The controller 3 allows a hand of the substrate transfer robot CR (SeeFIG. 1) holding a substrate W to enter the inside of the chamber 7 in astate in which all of the nozzles and the like have retreated from abovethe spin chuck 8, and, as a result, the substrate W is delivered to thespin chuck 8, and is held by the spin chuck 8 in a state in which itsfront surface (device forming surface) is directed upwardly (SubstrateHolding Step).

The controller 3 allows the spin motor M to start rotating the substrateW (S2 of FIG. 4. Substrate Rotating Step). The substrate W is raised inrotational speed to a predetermined liquid processing speed (within arange of 300 to 1500 rpm and of, for example, 500 rpm), and ismaintained at the liquid processing speed.

When the rotation speed of the substrate W reaches the liquid processingspeed, the controller 3 executes an SPM step (Chemical liquid SupplyStep) S3.

In detail, the controller 3 allows the SPM nozzle 18 to move from theretreat position to the processing position by controlling the nozzlemoving unit 20. Furthermore, the controller 3 simultaneously opens thesulfuric acid valve 24 and the hydrogen-peroxide-water valve 36. Hence,H₂SO₄ is supplied to the SPM nozzle 18 through the sulfuric acid piping23, and H₂O₂ is supplied to the SPM nozzle 18 through thehydrogen-peroxide-water piping 35. H₂SO₄ and H₂O₂ are mixed togetherinside the SPM nozzle 18, and a high-temperature SPM (for example, 160°C. to 220° C.) is generated. This SPM is expelled from the expellingport of the SPM nozzle 18, and lands on the central portion of the uppersurface of the substrate W. In the present preferred embodiment, theconcentration of the SPM is kept constant over the entire period of theSPM step S3.

The SPM expelled from the SPM nozzle 18 lands on the upper surface ofthe substrate W, and then flows outwardly along the upper surface of thesubstrate W because of a centrifugal force. Therefore, the SPM issupplied to the whole area of the upper surface of the substrate W, anda liquid film of the SPM with which the whole area of the upper surfaceof the substrate W is covered is formed on the substrate W. Hence, theresist and the SPM chemically react with each other, and the resist onthe substrate W is removed from the substrate W by means of the SPM. TheSPM that has moved to a peripheral edge portion of the substrate Wscatters sidewardly from the peripheral edge portion of the substrate W.

In the SPM step S3, the controller 3 may allow the SPM nozzle 18 to movebetween a peripheral edge position facing the peripheral edge portion ofthe upper surface of the substrate W and a central position facing thecentral portion of the upper surface of the substrate W by controllingthe nozzle moving unit 20. In this case, the landing position of the SPMin the upper surface of the substrate W is scanned over the whole areaof the upper surface of the substrate W. This makes it possible toevenly process the whole area of the upper surface of the substrate W.

When a predetermined period of time elapses from the start of theexpelling of the SPM, the controller 3 closes the sulfuric acid valve 24and the hydrogen-peroxide-water valve 36, and stops expelling the SPMfrom the SPM nozzle 18. Hence, the SPM step S3 is ended. Thereafter, thecontroller 3 allows the SPM nozzle 18 to return to the retreat positionby controlling the nozzle moving unit 20 (See FIG. 2).

Thereafter, a rinse step (Different-Liquid Supply Step. S4 of FIG. 4) ofsupplying a rinse liquid to the substrate W is performed. In detail, thecontroller 3 opens the rinse liquid valve 49, and allows the rinseliquid nozzle 47 to expel a rinse liquid toward the central portion ofthe upper surface of the substrate W. The rinse liquid expelled from therinse liquid nozzle 47 lands on the central portion of the upper surfaceof the substrate W covered with the SPM. The rinse liquid that haslanded on the central portion of the upper surface of the substrate Wreceives a centrifugal force generated by the rotation of the substrateW, and flows on the upper surface of the substrate W toward theperipheral edge portion of the substrate W. Hence, the SPM on thesubstrate W is swept away outwardly by means of the rinse liquid, and isdrained to surroundings of the substrate W. Hence, the SPM and theresist (i.e., resist residue) are rinsed away in the whole area of theupper surface of the substrate W. The resist residue is, for example,carbide. When a predetermined period of time elapses from the start ofthe rinse step S4, the controller 3 closes the rinse liquid valve 49,and allows the rinse liquid nozzle 47 to stop expelling the rinse liquidtherefrom.

Thereafter, a drying step (S5 of FIG. 4) of drying the substrate W isperformed.

In the drying step S5, in detail, the controller 3 controls and allowsthe spin motor M to accelerate the substrate W to a drying rotationspeed (for example, several thousand rpm) greater than the rotationspeed employed until the SPM step S3 and until the rinse step S4 and torotate the substrate W at the drying rotation speed. Hence, a largecentrifugal force is applied to a liquid on the substrate W, and theliquid adhering to the substrate W is shaken off to the surroundings ofthe substrate W. The liquid is removed from the substrate Win this way,and the substrate W is dried.

Thereafter, when a predetermined period of time elapses after thehigh-speed rotation of the substrate W is started, the controller 3controls and allows the spin motor M to stop the rotation of thesubstrate W by means of the spin chuck 8 (S6 of FIG. 4).

Thereafter, the substrate W is carried out from the inside of thechamber 7 (S7 of FIG. 4). In detail, the controller 3 allows the hand ofthe substrate transfer robot CR to enter the inside of the chamber 7.Thereafter, the controller 3 allows the hand of the substrate transferrobot CR to hold the substrate W on the spin chuck 8. Thereafter, thecontroller 3 allows the hand of the substrate transfer robot CR toretreat from the inside of the chamber 7. Hence, the substrate W inwhich the resist has been removed from the front surface (the deviceforming surface) is carried out of the chamber 7.

FIG. 5 is a timing chart for describing up-and-down timings of the firstand second guards 43 and 44 in the SPM step S3. FIGS. 6A to 6C areillustrative views to describe the SPM step S3. FIG. 6D is anillustrative view to describe the drying step S5.

With reference to FIG. 2 to FIG. 5, a description will be given ofup-and-down movements of the first and second guards 43 and 44 (i.e.,switching of guards facing the peripheral end surface of the substrate W(guards arranged at a position at which a processing liquid expelledfrom the substrate W can be captured) (Guard Switching Step)) in thesubstrate processing example shown in FIG. 4. Reference is appropriatelymade to FIGS. 6A to 6D.

The SPM step S3 includes a first step T1 in which the processing cup 11is in a first guard facing state, a second step T2 in which theprocessing cup 11 is in a first guard cleaning state, and a third stepT3 in which the processing cup 11 is in a second guard facing state.

Many resist residues (foreign substances) exist on the front surface ofthe substrate W for a time after the SPM step S3 is started, andtherefore a large amount of resist residues are included in the SPM thatis scattered (is a expelled) from the substrate W for this period oftime. The SPM including a large amount of resist residues is unsuitablefor reusing, and therefore it is preferable to discard the SPM withoutcollecting it. On the other hand, it is preferable to minimize thediscarding of the SPM from the viewpoint of environmentalconsiderations, and, if the SPM expelled from the substrate W comes notto include resist residues, it is preferable to collect and reuse theSPM. In this specification, the expression “resist residues are notincluded” semantically includes a case of “resist residues are notincluded at all,” a case of “resist residues are hardly included,” and acase of “only a tiny amount of resist residues are included.”

In the substrate processing example shown in FIG. 4, the processing cup11 is in a retreated state before the substrate is carried in (S1). Inthe SPM step S3, the SPM nozzle 18 is arranged at the processingposition, and then the controller 3 controls and allows the guardelevating/lowering unit 46 to raise the first to third guards 43 to 45to the upper position, and, as a result, the peripheral end surface ofthe substrate W is allowed to face the first guard 43 as shown in FIG.6A (achievement of the first guard facing state). Hence, the first stepT1 is started. This state is maintained in the first step T1(Processing-Height Maintaining Step).

In the SPM step S3 (first step T1), the SPM scattering from theperipheral edge portion of the substrate W lands on an annular firstregion R1 of the inner wall 43 a of the first guard 43. The SPM capturedby the inner wall 43 a flows down along the inner wall 43 a of the firstguard 43, and is received by the first cup 41, and is sent to the firstdrain piping 52. The SPM sent to the first drain piping 52 is sent todisposal processing facilities provided outside the apparatus.

As described above, a large amount of resist residues are included inthe SPM scattered (expelled) from the substrate W for a time after theSPM step S3 is started. In the first step T1, the SPM that has beenexpelled from the substrate W and that includes resist residues isdrained through the first flow space 101. That is, the SPM is notrecovered and reused.

In the first step T1, the SPM that has landed on the first region R1 ofthe inner wall 43 a adheres to the inner wall 43 a of the first guard 43while spreading in the up-down direction as shown in FIG. 6A and FIG.6B. Let it be assumed that an upper end of a region at which the SPM,which has landed on the first region R1, arrives is defined as anarrival-region upper end (an upper end of an arrival region) UR. Resistresidues RR (see FIG. 6A and FIG. 6B) are included in the SPM scatteredfrom the substrate W, and therefore there is a fear that resist residuesRR will adhere to a region below the annular arrival-region upper end URin the inner wall 43 a of the first guard 43.

When a predetermined cleaning period of time elapses from the start ofthe expelling of an SPM, the first step T1 is ended, and then the secondstep T2 is started. The cleaning period of time is a predeterminedperiod of time subsequent to a state in which an SPM expelled from thesubstrate W no longer includes resist residues from the start of theexpelling of an SPM. The cleaning period of time is calculated by apre-experiment or the like, and is stored in the storage unit of thecontroller 3. The cleaning period of time may be variously determineddepending on various conditions (at least one among a condition (doseamount) for ion implantation processing of a to-be-processed substrateW, the kind of a resist formed on the substrate W, the supply flow rateof an SPM in the first step T1, and the supply concentration of an SPMin the first step T1).

In detail, the controller 3 controls the guard elevating/lowering unit46, and lowers the first guard 43 to the cleaning height position WP(see FIG. 6B) from the upper position PP (see FIG. 6A) at which thefirst guard 43 has been so far arranged as shown in FIG. 6B (achievementof the first guard cleaning state). Thereafter, the controller 3 allowsthe first guard 43 to be maintained at the cleaning height position WP(cleaning height maintaining step).

In the second step T2, the concentration of an SPM expelled from the SPMnozzle 18, the flow rate of an SPM, the rotation speed of the substrateW are the same as in the first step T1. In the second step T2, an SPMscattering from the peripheral edge portion of the substrate W lands onan annular second region R2 of the inner wall 43 a of the first guard 43(i.e., a position at which the inner wall 43 a of the first guard 43arranged at the cleaning height position WP captures the SPM). In theinner wall 43 a of the first guard 43, the second region R2 is arrangedabove the first region R1. In more detail, the second region R2 is setat a higher position than the arrival-region upper end UR. Therefore, itis possible to excellently wash away substantially all of the SPMincluding resist residues, which adhere to a region below the annulararrival-region upper end UR of the inner wall 43 a, by means of the SPMcaptured by the first guard 43 arranged at the cleaning height positionWP. This cleaning operation is fully satisfied if resist residues can becleaned away from the inner wall 43 a. Therefore, the inner wall 43 a iscleaned by use of the SPM that is the chemical liquid.

The SPM flowing down the inner wall 43 a of the first guard 43 is sentto the disposal processing facilities provided outside the apparatusthrough the first cup 41 and through the first drain piping 52. That is,in the second step T2, the SPM scattering from the peripheral edgeportion of the substrate W is likewise drained through the first flowspace 101. That is, the SPM is not recovered and reused.

When a predetermined cleaning period of time elapses from the placementof the first guard 43 to the cleaning height position WP, the secondstep T2 is ended, and then the third step T3 is started.

That is, the guard facing the peripheral end surface of the substrate Wis switched from the first guard 43 to the second guard 44 (GuardSwitching Step). In detail, the controller 3 controls the guardelevating/lowering unit 46, and lowers the first guard 43 to the lowerposition from the cleaning height position WP (see FIG. 6B) at which thefirst guard 43 has been so far arranged as shown in FIG. 6C (achievementof the second guard facing state). When the guard is switched in thisway, both the flow rate of the SPM expelled from the SPM nozzle 18 andthe rotation speed of the substrate W do not undergo a change.

The cleaning period of time mentioned here is a period of time longenough to remove resist residues from the inner wall 43 a of the firstguard 43. The cleaning period of time is calculated by a pre-experimentor the like, and is stored in the storage unit of the controller 3.

In the third step T3, the concentration of an SPM expelled from the SPMnozzle 18, the flow rate of an SPM, the rotation speed of the substrateW are the same as in the first step T1. In the third step T3, an SPMscattering from the peripheral edge portion of the substrate W iscaptured by the inner wall 44a of the second guard 44. Thereafter, theSPM flowing down along the inner wall 44a of the second guard 44 is sentto the recovery tank 29 of the sulfuric acid supply portion 26 throughthe second cup 42, the common piping 55, and the recovery piping 56.That is, in the third step T3, the SPM scattering from the peripheraledge portion of the substrate W is recovered through the second flowspace 102, and is reused.

Thereafter, when the end timing of the SPM step S3 is reached, the thirdstep T3 is also ended.

In the rinse step S4 executed subsequently to the SPM step S3, theprocessing cup 11 is in the first guard facing state. Therefore, afterthe end of the third step T3, the controller 3 controls the guardelevating/lowering unit 46, and raises the first guard 43 to the upperposition (achievement of the first guard facing state).

In the drying step S5, the processing cup 11 is in the third guardfacing state. Therefore, after the end of the rinse step S4, thecontroller 3 controls the guard elevating/lowering unit 46, and lowersthe first and second guards 43 and 44 to the lower position (achievementof the third guard facing state is realized).

Before the substrate W is carried out (S7 of FIG. 4), the controller 3controls the guard elevating/lowering unit 46, and lowers the thirdguard 45 to the lower position. Hence, all of the first to third guards43 to 45 are arranged at the lower position (achievement of theretreated state).

As described above, according to the present preferred embodiment, theflow destination of the SPM expelled from the substrate W is switchedfrom the first flow space 101 of the processing cup 11 to the secondflow space 102 in parallel with the SPM step S3. This makes it possibleto allow an SPM including resist residues and an SPM not includingresist residues to flow to the first and second flow spaces 101 and 102that are mutually different spaces in the processing cup 11. This makesit possible to allow an SPM including resist residues and an SPM notincluding resist residues to flow mutually separately inside theprocessing cup 11.

Also, the SPM flowing in the first flow space 101 is guided to the firstdrain piping 52, and the SPM flowing in the second flow space 102 isguided to the recovery piping 56. Therefore, the SPM including resistresidues flows in the first flow space 101, and is guided to the firstdrain piping 52, whereas the SPM not including resist residues flows inthe second flow space 102, and is guided to the recovery piping 56.Hence, it is possible to collect only the SPM not including resistresidues. Therefore, it is possible to effectively restrain or preventresist residues from being mixed with the SPM recovered as above.

Also, it is possible to switch the flow destination of an SPM expelledfrom the substrate W between the first flow space 101 and the secondflow space 102 by switching the guard facing the peripheral end surfaceof the substrate W between the first guard 43 and the second guard 44.This makes it possible to easily switch the flow destination of an SPMexpelled from the substrate W from one to the other.

Also, the first guard 43 and the second guard 44 are mutually adjoiningguards, and therefore it is possible to allow the second guard 44 toface the peripheral end surface of the substrate W merely by loweringthe first guard 43. Hence, it is possible to smoothly perform switchingbetween the guards facing the peripheral end surface of the substrate W.

Also, in parallel with guard switching, an SPM is continuously suppliedto the substrate W over the entire period of the up-and-down movement ofthe first guard 43. In this case, it is possible to make the period oftime required in the SPM step S3 shorter, and it is possible to furtherimprove throughput than in a case in which the supply of an SPM to thesubstrate W is stopped in the up-and-down movement of the first guard43.

Also, according to the present preferred embodiment, in the SPM step S3,the first guard 43 is positionally changed to the cleaning heightposition WP set below the upper position PP from the upper position PPat which the first guard 43 has been so far arranged, and then the firstguard 43 is maintained at the cleaning height position WP for apredetermined period of time.

Both in a state in which the first guard 43 is arranged at the upperposition PP and in a state in which the first guard 43 is arranged atthe cleaning height position WP, an SPM expelled from the substrate W iscaptured by the inner wall 43 a of the first guard 43. The SPM capturedby the inner wall 43 a of the first guard 43 flows downwardly because ofits own weight.

Also, in the inner wall 43 a of the first guard 43, the second region R2is set at a higher position than the arrival-region upper end UR.Therefore, it is possible to excellently wash away substantially all ofthe SPM including resist residues, which adhere to a region below theannular arrival-region upper end UR of the inner wall 43 a, by means ofthe SPM captured by the first guard 43 arranged at the cleaning heightposition WP.

Also, prior to the switching of the guard facing the peripheral endsurface of the substrate W from the first guard 43 to the second guard44, the first guard 43 is positionally changed to the cleaning heightposition WP from the upper position PP at which the first guard 43 hasbeen so far arranged, and then the first guard 43 is maintained at thecleaning height position WP for a predetermined period of time. Prior tothe switching between the first and second guards 43 and 44, the firstguard 43 is arranged at the cleaning height position WP, and the innerwall 43 a of the first guard 43 is cleaned, and therefore it is possibleto remove resist residues from the inner wall 43 a of the first guard 43before the first guard 43 finishes being used.

Also, the guard facing the peripheral end surface of the substrate W isswitched from the first guard 43 to the second guard 44 without allowingthe first guard 43 to be again arranged at the processing heightposition after the first guard 43 is arranged at the cleaning heightposition. This makes it possible to perform switching between the firstand second guards 43 and 44 immediately after the first guard 43 iscleaned, and hence makes it possible to shorten the processing time ofthe SPM step S3.

Although the preferred embodiment of the present invention has beendescribed as above, the present invention can be embodied in othermodes.

For example, although the cleaning of the first guard 43 (the secondstep T2) is performed only once in the SPM step S3 as described above,the cleaning of the first guard 43 (the second step T2) may be performeda plurality of times in the SPM step S3.

Also, although guard switching (transition to the third step T3) isperformed immediately after the first guard 43 is cleaned (the secondstep T2) as described above, guard switching (transition to the thirdstep T3) may be performed immediately after the first step T1 isexecuted (i.e., after the first facing state of the processing cup 11 isachieved) after the first guard 43 is cleaned (the second step T2).

Also, the third step T3 may be omitted. In this case, the SPM step S3includes the first step T1 and the second step T2.

Also, although guard cleaning is performed in the first guard 43, guardcleaning may be performed in the other guards (i.e., the second guard 44and/or the third guard 45).

Also, although the recovered SPM is reused as sulfuric acid in thesubstrate processing apparatus 1 according to the aforementionedpreferred embodiment as described as a configuration example, therecovered SPM may be used in another device or the like without beingreused in the substrate processing apparatus 1.

Also, the recovery piping 56 may be connected directly to the bottomportion of the second cup 42 without being connected through the commonpiping 55. An SPM stored in the second cup 42 is recovered into thesulfuric acid supply portion 26 through the common piping 55. In thiscase, the second drain piping 57 and the switching unit (the recoveryvalve 58 and the drain valve 59) are eliminated.

Also, in the aforementioned substrate processing example, a firstcleaning step in which the upper surface of the substrate W is cleanedby use of a first cleaning chemical liquid may be executed prior to theSPM step S3. For example, hydrofluoric acid (HF) can be mentioned as thefirst cleaning chemical liquid. The first cleaning step is executed in astate in which the processing cup 11 is in the first guard facing state.Thereafter, a second rinse step in which the first cleaning chemicalliquid is cleaned away by a rinse liquid is executed when the firstcleaning step is executed. The second rinse step is executed in a statein which the processing cup 11 is in the first guard facing state.

Also, in the aforementioned substrate processing example, a hydrogenperoxide water supply step in which H202 is supplied to the uppersurface (the front surface) of the substrate W may be executed prior tothe rinse step S4 after the SPM step S3. In this case, the controller 3closes only the sulfuric acid valve 24 while maintaining thehydrogen-peroxide-water valve 36 in an open state. Hence, only H₂O₂ issupplied to the SPM nozzle 18, and H₂O₂ is expelled from the expellingport of the SPM nozzle 18. In the hydrogen peroxide water supply step,the processing cup 11 is in the first guard facing state.

Also, in the aforementioned substrate processing example, a secondcleaning step in which the upper surface of the substrate W is cleanedby use of a second cleaning chemical liquid may be executed after therinse step S4. For example, SC1 (a mixed liquid that includes NH₄OH andH₂O₂) can be mentioned as the second cleaning chemical liquid. Thesecond cleaning step is executed in a state in which the processing cup11 is in the first guard facing state. Thereafter, a third rinse step inwhich the second cleaning chemical liquid is cleaned away by a rinseliquid is executed when the second cleaning step is executed. The thirdrinse step is executed in a state in which the processing cup 11 is inthe first guard facing state.

Also, an organic-solvent replacement step in which an organic solvent(drying liquid) that has a small surface tension is supplied, and then arinse liquid on the upper surface of the substrate W is rearranged bythe organic solvent may be executed prior to the drying step S5. Theorganic-solvent replacement step is executed in a state in which theprocessing cup 11 is in the third guard facing state.

Also, although a nozzle mixing type unit in which H₂SO₄ and H₂O₂ aremixed together inside the SPM nozzle 18 is mentioned as the SPM supplyunit 9 as described in the first and second preferred embodiments as anexample, a piping mixing type unit in which H₂SO₄ and H₂O₂ are mixedtogether in a mixing portion provided to be connected to an upstreamside of the SPM nozzle 18 through a piping can be employed instead.

Also, although, for example, resist-removing processing is mentioned inthe substrate processing example of FIG. 4, processing for removingother organic substances by use of an SPM may be employed without beinglimited to a resist.

Also, a chemical liquid that is supplied to the substrate W is notlimited to the SPM, and other chemical liquids maybe employed. BHF, DHF(dilute hydrofluoric acid), SC1 (ammonia-hydrogen peroxide mixture), SC2(hydrochloric acid-hydrogen peroxide mixture), organic solvents (forexample, NMP and acetone), nitric acid, ammonium phosphate, citric acid,sulfuric acid, dilute sulfuric acid, hydrofluoric nitric acid, undilutedHF, aqua regia, organic acids, such as TMAH (tetramethylammoniumhydroxide aqueous solution), etc., and liquid mixtures of such organicacids can be mentioned. Besides, O₃ water may be employed. In this case,a metal, Si, or an organic substance is mentioned as a foreign substanceincluded in the chemical liquid.

Also, although the processing cup 11 is a three-stage cup as describedas an example, the processing cup 11 may be a one-stage cup (singlecup), or may be a two-stage cup, or may be a multistage cup greater thanfour stages.

Also, although the substrate processing apparatus 1 is an apparatus thatprocesses a front surface of a substrate W of a semiconductor wafer asdescribed in the aforementioned preferred embodiment, the substrateprocessing apparatus may be an apparatus that processes substrates suchas substrates for liquid crystal display devices, substrates for FPDs(Flat Panel Displays) such as an organic EL (electroluminescence)display device, etc., substrates for optical disks, substrates formagnetic disks, substrates for magneto-optical disks, substrates forphotomasks, ceramic substrates, or substrates for solar cells, etc.

Although the preferred embodiments of the present invention have beendescribed in detail, these preferred embodiments are merely concreteexamples used to clarify the technical content of the present invention,and the present invention should not be understood by being limited tothese concrete examples, and the scope of the present invention islimited solely by the appended claims.

What is claimed is:
 1. A substrate processing apparatus comprising: a substrate holding unit that holds a substrate; a rotation unit that rotates a substrate held by the substrate holding unit around a rotational axis passing through a central portion of the substrate; a chemical liquid supply unit that supplies a chemical liquid to a main surface of a substrate held by the substrate holding unit; a cylindrical first guard that surrounds a periphery of the substrate holding unit and that captures a liquid expelled from a substrate held by the substrate holding unit; a guard elevating/lowering unit that raises and lowers the first guard; and a controller that controls the rotation unit, the chemical liquid supply unit, and the guard elevating/lowering unit, the controller executing: a chemical liquid supply step of supplying a chemical liquid by the chemical liquid supply unit to a main surface of a substrate held by the substrate holding unit while rotating the substrate around the rotational axis by the rotation unit; a processing-height maintaining step of maintaining the first guard at a processing height position by the guard elevating/lowering unit in parallel with the chemical liquid supply step such that the first guard captures the chemical liquid supplied to the main surface of the substrate and expelled from the substrate to be incident on a first region of the first guard; and a cleaning-height maintaining step of maintaining the first guard at a cleaning height position lower than the processing height position by the guard elevating/lowering unit in parallel with the chemical liquid supply step after the processing-height maintaining step such that the first guard captures the chemical liquid supplied to the main surface of the substrate and expelled from the substrate to be incident on a second region of the first guard that is higher in position than the first region with respect to the first guard.
 2. The substrate processing apparatus according to claim 1, wherein the second region is set above an upper end to which the chemical liquid incident on the first region spreads on the first guard during the processing-height maintaining step.
 3. The substrate processing apparatus according to claim 1, further comprising a cylindrical second guard that is provided separately from the first guard and that surrounds a periphery of the substrate holding unit and that captures a liquid expelled from a substrate held by the substrate holding unit, wherein the controller further executes a guard switching step of, after the cleaning-height maintaining step, arranging, in parallel with the chemical liquid supply step, the second guard such that the second guard, in place of the first guard, captures the chemical liquid supplied to the main surface of the substrate and expelled from the substrate to be incident on the second guard.
 4. The substrate processing apparatus according to claim 3, wherein the controller executes the guard switching step after the cleaning-height maintaining step, without again executing the processing-height maintaining step.
 5. The substrate processing apparatus according to claim 1, further comprising a different-liquid supply unit that supplies another processing liquid to a main surface of a substrate held by the substrate holding unit, the other processing liquid differing in kind from the chemical liquid supplied by the chemical liquid supply unit, wherein the controller further executes: a different-liquid supply step of supplying the other processing liquid to the main surface of the substrate by the different-liquid supply unit while rotating the substrate around the rotational axis by the rotation unit; and a step of placing the first guard at a position at which the first guard captures the other processing liquid supplied to the main surface of the substrate and expelled from the substrate to be incident on the first guard in parallel with the different-liquid supply step.
 6. The substrate processing apparatus according to claim 1, wherein a resist is formed on the main surface of the substrate, and the chemical liquid supplied to the main surface of the substrate in the chemical liquid supply step includes an SPM (sulfuric acid/hydrogen peroxide mixture). 